Valence

3 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Valance \Val"ance\, n. [Perhaps fr. OF. avalant descending,
     hanging down, p. pr. of avaler to go down, let down, descend
     (cf. {Avalanche}); but probably from the town of Valence in
     France.]
     [1913 Webster]
     1. Hanging drapery for a bed, couch, window, or the like,


        especially that which hangs around a bedstead, from the
        bed to the floor. [Written also {valence}.]
        [1913 Webster]
  
              Valance of Venice gold in needlework. --Shak.
        [1913 Webster]
  
     2. The drooping edging of the lid of a trunk, which covers
        the joint when the lid is closed.
        [1913 Webster]

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Valence \Va"lence\, n. [From L. valens, -entis, p. pr. of valere
     to have power, to be strong. See {Valiant}.] (Chem.)
     The degree of combining power of an atom (or radical) as
     shown by the number of atoms of hydrogen (or of other monads,
     as chlorine, sodium, etc.) with which it will combine, or for
     which it can be substituted, or with which it can be
     compared; thus, an atom of hydrogen is a monad, and has a
     valence of one; the atoms of oxygen, nitrogen, and carbon are
     respectively dyads, triads, and tetrads, and have a valence
     respectively of two, three, and four.
     [1913 Webster]
  
     Note: The valence of certain elements varies in different
           compounds. Valence in degree may extend as high as
           seven or eight, as in the cases of iodine and osmium
           respectively. The doctrine of valence has been of
           fundamental importance in distinguishing the
           equivalence from the atomic weight, and is an essential
           factor in explaining the chemical structures of
           compounds.
           [1913 Webster]

From WordNet (r) 2.0 [wn]:

  valence
       n 1: (biology) a relative capacity to unite or react or interact
            as with antigens or a biological substrate [syn: {valency}]
       2: (chemistry) a property of atoms or radicals; their combining
          power given in terms of the number of hydrogen atoms (or
          the equivalent) [syn: {valency}]